基于快速切换的代理移动IPv6路由优化方案

针对代理移动IPv6移动节点(MN)切换后重建优化路径时延较长问题,提出一种基于快速切换的路由优化方案。新方案通过在MN快速切换过程中由旧移动接入网关提前发起路由优化,实现了优化路径的快速重建。性能分析表明,新域内路由优化方案比局部移动锚点发起的路由优化方案减少了21.7%的路由优化平均费用和45.4%的路由优化状态建立时延;新域间路由优化方案比现有域间切换及路由优化方案减少了72.2%的路由优化状态建立时延。     

PMIPv6网络域内切换路由优化方法的改进

针对代理移动IPv6（PMIPv6）中域内切换时延较大的问题,提出了基于LMA的域内切换路由优化方法。在新方法中,当移动节点链接到的新的移动接入网关向LMA发送代理绑定更新（PBU）消息后,LMA向相关的移动接入网关回发通信绑定更新（CBU）消息。分析和仿真结果表明,优化方法实现了切换后由先前的优化路径平滑且快速地过渡到新的优化路径,从而新方法能够有效地减少切换时延同时降低了切换路由优化过程中包传递发生乱序的可能性。     

层次型移动IPv6优化方案

移动且不需要改变IP地址是移动IPv6的关键所在,而移动IPv6的关键技术就在移动过程中的切换。如何降低切换延时是衡量移动IPv6切换性能的标准。为此,针对移动主机在外地网络内的频繁切换已提出层次移动IPv6,用以降低时延,针对二层网络触发的切换预期已提出移动IPv6快速切换。本文提出一种以层次型移动IPv6快速切换协议(FHMIPv6)为基础的改进方案,首先针对快速切换的链路层时延引入缓存机制,然后主要针对域间切换MAP无法减少注册时延的问题,引入功能路由概念,提出最优功能路由算法,以减少切换时延和丢包率。实验分析表明,相比层次型移动IPv6快速切换方法,该方法有很大程度的改进。     

基于PMIPv6的域间切换管理方法及性能分析*

针对代理移动IPv6（PMIPv6）中域间切换时延较大的问题,提出了一种基于PMIPv6的域间切换管理方案。新方案通过在PMIPv6域间发送PBU绑定更新消息,使得切换目标PMIPv6域提前知道移动节点（MN）的家乡网络前缀,避免了移动节点参与移动性管理及重新配置转交地址,从而有效减小了切换时延。分析和仿真结果表明,与现有的全局移动性管理方案移动IPv6和快速移动IPv6相比较,新方案更加适应移动性管理中低时延、低复杂度、易于操作的要求。     

基于位置预查询的因特网移动支持方案

提出一种预查询移动支持方案(mobile Internet protocol_based on location pre-query,简称MIP_Q),以解决家乡网络的流量瓶颈和单点故障问题,从而提高移动通信的效率和可靠性.MIP_Q通过扩展域名服务系统管理和跟踪移动节点的当前位置信息,省去了家乡代理;采用并行切换控制方式,同时避免了MIP(mobile Internet protocol,简称MIP)中的三角路由和隧道路由问题;借助有效的计算方法,分析和比较了MIP_Q与MIP,MIP_LR的平均移动通信成本和切换时延;在实现方面与广泛应用的广域蜂窝移动网络进行了类比.结果表明:MIP_Q在切换效率和新增实体数等方面优于同类方案;MIP_Q可以极大地降低节点的移动通信成本,减小切换时延;MIP_Q具有良好的可行性.最后提出MIP_Q的仿真和实现方案.     

基于MA和SHORT技术的移动ad hoc网络路由方案

由于传统的AODV路由协议和基于移动代理的路由方案存在着不少缺点,论文通过两者的结合,提出了一种混合式的移动adhoc网络路由方案,从而降低了纯按需路由协议寻找路由的时延。并且结合已有的SHORT路由技术监控路由,随时发现捷径,从而在很小花费开销的情况下优化路由,节省带宽,减少时延。最后的仿真结果证明了论文所提出的方案的可行性。     

基于群集移动节点的切换算法

无线蜂窝网的信号切换依赖IP层的移动切换,IETF提出的代理移动IPv6(PMIPv6)协议可以保证移动终端应用IPv6网的快速切换,但是它在切换时延方面仍然无法保证实时通信的服务质量。研究基于PMIPv6协议,提出群集移动节点(CMN)算法,应用媒体无关切换(MIH)技术,减少了大量移动节点,同时提出切换请求时系统时延增大的问题,扩展原始代理绑定更新消息结构(A-PBU)。最后模拟网络模型和节点移动模型,从切换时延方面分析算法的有效性。实验结果表明,系统应用CMN算法与原始切换算法相比可以大大降低切换时延。     

基于快速切换的MIPv6与PMIPv6域间互通优化方案

移动IPv6是一种需要主机参与管理的移动管理协议,而代理移动IPv6不需要主机参与移动管理.在成熟的MIPv6环境下使用PMIPv6,需考虑二者互通问题.已提出的互通方案多属硬切换,没有考虑切换的时延.运用域内快速切换思想,提出一种优化的域间快速切换方案,并对比优化方案和已有切换方案的网络切换时延.分析结果显示,优化方案的性能更优.     

改进的PMIPv6域内路由优化策略

代理移动IPv6移动节点发生域内切换时,存在着重建路由优化路径时延长、切换开销大的问题,为此,提出一种改进的代理移动IPv6域内路由优化方案.在移动节点即将发生域内切换时,由新接入的移动网关发起切换,减少了切换过程中本地移动锚点的参与,在移动节点接入新网络之前完成优化路径的建立.仿真实验结果表明,新方案在切换时延和切换开销方面的性能优于原有的代理移动IPv6域内路由优化方案.     

FHMIPv6网络中快速的乒乓切换方案

针对现有移动网络中乒乓切换问题导致的高切换延迟的情况,提出一种在FHMIPv6网络基础上的快速的切换方案.该方案提出了切换的门限阈值以及隧道状态,门限阈值决定切换发生的起点,隧道间的状态则根据需要快速激活或终止通信链路.方案优点是当移动节点在边界区域来回切换时,提供快速切换机制,减少了切换时延,合理地处理新旧AR通信隧道激活,睡眠以及终止,合理地利用带宽资源,在降低时延上保证了一定的服务质量(QoS).通过实验仿真验证了该切换方案对减少时延的有效性.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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